Industry Overview
Steel structures and oversized workpieces are painted where the crane sets them down: a telescopic spray booth extends over the part, with blasting, airless application and VOC treatment sized to the largest piece.
Structural steel, bridge girders, pressure vessels, hull blocks, crane girders and heavy machine frames share one problem: the workpiece is too long, too heavy or too irregular to travel through a conveyorised coating line. It is moved by overhead crane or transfer cart, coated with a few layers of high-build liquid paint, and stays in one place while each coat dries.
A fixed spray booth large enough for a 20 m girder blocks the crane bay permanently, and spraying in the open workshop leaves overspray and solvent vapour in the air. The paint shop for this industry is therefore built around an enclosure that opens for the crane and closes for painting, with extraction and exhaust treatment connected at the fixed end.
Typical Workpieces
- H-beams, box columns and trusses for steel buildings
- Bridge plate girders and crane girders up to 20 m long
- Pressure vessels, storage tank shell plates and pipe spools
- Oil and gas process skids
- Hull blocks and ship sub-assemblies
- Excavator buckets, booms and other construction machinery attachments
- Mining truck bodies and mill shells in rebuild shops
- Trailer chassis and agricultural equipment frames
Industry Coating Challenges
Each industry faces unique coating challenges. MUSI's solutions are designed to address these pain points directly:
The workpiece cannot come to the booth
Large fabrications are set down by overhead crane, so the painting area has to be open from above until the part is in place. A telescopic booth folds back to about 15% of its extended length — roughly 3 m for a 20 m booth — and travels on floor rails to cover the workpiece once the crane has left.
High-build coatings mean heavy overspray
Zinc-rich primers and high-build epoxy coats are applied by airless spray in thick films, and a large share of the overspray has to be caught before it reaches the fan. Paint mist is captured either by a dry filter (labyrinth paper plus glass-fibre bags) or by an oil-film purifier, each removing 98% or more of the mist.
Intermittent painting changes the VOC equation
A fabrication shop paints in batches, not around the clock, so the exhaust system is sized for the solvent load of a paint day rather than for continuous production. Activated carbon, UV photo-oxidation or carbon adsorption-desorption with catalytic oxidation (RCO) is selected for exhaust volumes of 30,000-80,000 m3/h, and two booths can share one RCO unit.
Surface preparation decides coating life
Mill scale and weld spatter have to be removed before the primer goes on. Blasting to Sa 2½ (ISO 8501-1) in a sandblasting room, with abrasive recovery and dust collection, is the step the whole coating system rests on.
Solvent atmosphere inside a fabric enclosure
The booth works with solvent-based paint inside flame-retardant PVC fabric, so the drive motors and LED lighting are explosion-proof, the cross-draft is kept at 0.3 m/s or more, and travel uses jog control with double limit switches at both ends.
Reference Booth Configurations
These are the configurations used in MUSI telescopic spray booth project designs. Each booth is sized to the largest workpiece the shop has to paint.
| Application | Internal size (L x W x H) | Paint mist capture | Exhaust treatment |
|---|---|---|---|
| Structural steel, bridge girders, crane girders, hull blocks | 20 x 10 x 4 m | Dry filter | Activated carbon plus UV photo-oxidation |
| Pressure vessels, mining equipment bodies | 12 x 7 x 4.5 m | Oil-film purifier | Carbon adsorption-desorption with RCO, 30,000 m3/h |
| Machinery attachments, trailer chassis | 12 x 5 x 4.1 m | Dry filter | Activated carbon, or one RCO shared by two booths |
| Process skids, tank shell plates, pipe spools | 13 x 5 x 3 m | Oil-film purifier | Activated carbon |
| Custom-engineered builds | Up to 100 x 35 x 9 m | Selected per project | Selected per project |
MUSI's Targeted Solutions
MUSI supplies the paint shop for large fabrications as one system — enclosure, paint mist capture, exhaust treatment and controls sized against the same workpiece envelope and the same paint schedule.
- Enclosure — the telescopic mobile spray booth, built in 1 m frame modules from Q235 steel frames and flame-retardant PVC fabric, up to 100 m long, 35 m wide and 9 m high.
- Surface preparation — a sandblasting room with abrasive recovery for fabrications that cannot pass through a shot blasting machine.
- Application — airless high-pressure spray for zinc-rich primers and high-build epoxy coats.
- Paint mist capture — a dry paint mist filter cabinet or an oil-film paint mist purifier, chosen by paint consumption and maintenance preference.
- Exhaust treatment — activated carbon adsorption or a catalytic oxidizer (RCO), matched to the solvent load of a paint day.
Key components are available from international brands such as SEW-EURODRIVE, Siemens, Schneider Electric and Graco, configurable per customer specification.
Recommended Equipment
Typical projects in this industry use the following MUSI products in combination — exact selection depends on workpiece specifics:
Telescopic Mobile Spray Booth
Sandblasting Room (Abrasive Blast Room)
Airless High-Pressure Spray
Dry Paint Mist Filter Cabinet
Oil-Film Paint Mist Purifier
Catalytic Oxidizer (RCO)
Featured Case Studies
Selected projects MUSI has delivered for clients in this industry. More projects in our Case Studies section:
Telescopic Spray Booth for a Structural Steel Fabricator, Vietnam
View Details
Oil-Film Telescopic Spray Booth with RCO for a Pressure Vessel Builder, Indonesia
View Details
20 m Telescopic Spray Booth for a Bridge Girder Fabricator, India
View Details
Telescopic Spray Booth for Hull Block Painting at a Shipyard, Philippines
View Details
Oil-Film Telescopic Spray Booth with RCO for a Mining Equipment Rebuild Shop, Kazakhstan
View Details
Telescopic Spray Booth for Trailer Chassis Painting, Australia
View DetailsProject References
For how the enclosure works and how to size it, see what a telescopic spray booth is, telescopic versus fixed spray booths for large workpieces and booth sizing, airflow and fan power. Machine parts that do travel on a conveyor are covered under heavy machinery coating.
Schedule a Consultation
Tell us the largest workpiece, the paint system and how many paint days you run each week, and we will come back with a booth layout rather than a price list. Talk to a MUSI engineer.
The optimal solution depends on your specific workpieces, capacity, facility, and budget. MUSI provides a free consultation service including:
- 1-on-1 process consultation with our engineers
- Preliminary CAD line layout
- Equipment list and preliminary quotation
- Reference cases from similar industries
- Welcome to visit MUSI's factory in Changzhou